Tertiary-tertiary bisperoxides

ABSTRACT

Tertiary-tertiary bisperoxides having the general formula:   WHEREIN R is an alkyl and R1 is an aryl or alkyl groups which have utility as crosslinking agents for polyethylene.

United States Patent [191 Gregorian et al.

[451 Oct. 9, 1973 .154] TERTIARY-TERTIARY BISPEROXIDES [75] Inventors: Razmlc S. Gregorian, Silver Spring; Richard A. Bafford, Baltimore, both of Md.

[73] Assignee: W. R. Grace & Co., New York,

[22] Filed: July 29, 1960 21 App]. No.: 46,096

Related U.S. Application Data [63] Continuation-impart of Ser. No. 946, Jan. 7, 1960,

Pat. No. 3,118,866.

[52] U.S. Cl. 260/610 R, 260/395, 260/94.9 GA

[51 Int. Cl C07c 73/00 [58] Field of Search 260/610, 610 R, 395.

[56] References Cited UNITED STATES PATENTS 2,403,758 7/1946 Rust 260/610 2,813,127 11/1957 White 260/610 2,916,481 12/1959 Gilmont 260/610 X 10/1960 Bankert 260/610 1/1964 Gregorian i. 260/610 OTHER PUBLICATIONS Organic Peroxides, Tahoisky et a1., Pg. 1, 1954.

Primary Examiner-Bernard Helfin AttorneyRichard P. Plunkett and Kenneth E. Prince [57] ABSTRACT Tertiary-tertiary bisperoxides having the general formula:

3 Claims, No Drawings TERTIARY-TERTIARY BISPEROXIDES This application is a continuation-in-part of application having Ser. No. 946 filed Jan. 7, 1960, now U.S. Pat. No. 3,1 18,866 which subsequently reissued as Re. 25,941. V

This invention relates the synthesis of a novel class of bisperoxides. More particularly this invention pertains to a novel class of tertiary-tertiary aralkyl bisperoxides.

The novel tertiary-tertiary bisperoxides of this invention have the general formula:

1;. 1 1 t n. a rit ir -r R1 It R R1 where R is an alkyl and R is an aryl or alkyl group.

The novel tertiary-tertiary bisperoxides of the present invention are prepared by acid-catalyzed condensa- 20 tion of a dihydroxy compound with a hydroperoxide. Recent art has taught the preparation of primarytertiary diperoxides of the general formula:

wherein R and R represent the same or different hydrocarbyl radicals, which comprises reacting a hydroperoxide and a bis-(halomethyl)-tetrahydrocarbylsubstituted benzene in the presence of a base. See U.S. Pat'.

No. 2,813,127. These afore-mentioned latter diperox- 3 ides have many drawbacks, however, that affect their commercial development. For example, these diperox ides cannot be made by the acid method (benzyl alcohols are polymerized by strong acids). Additionally,

these diperoxides are rapidly decomposed by strong bases. See U.S. Pat. No. 2,813,127 column 3, lines 5-12 and 49-50, and also Organic Peroxides, A.V. Tobolsky and R. B. Mesrobian, page 122, lnterscience Publishers, Inc., New York, N.Y., 1954. Because of said base decomposition these latter diperoxides give poor yields on synthesis and great care must be taken to maintain pH control. Furthermore, to diminish the base-catalyzed decomposition of the resulting diperoxide product, it is necessary to have blocking alkyl groups ortho to the primary group. By blocking alkyl groups is meant a crowding of alkyl groups about the benzylic hydrogens to hinder abstraction of said hydrogens by a base.

On the other hand the novel tertiary-tertiary bisperoxides of the present invention are not decomposed by base, but are insensitive thereto. This is important in ,rubber curing when the bisperoxides are admixed with compounds such as carbon black, which can range from acidic to basic. The novel bisperoxides of this invention have improved heat stability and therefore can be used in curing rubber. An additional use is as a crosslinking agent for polyethylene which will be more fully described hereinafter.

Summarily, tertiary-tertiary aralkyl bisperoxides of 6 the formula:

R R R1 are produced in accordance with the instant invention by reacting a mole of an alcohol of the formula:

with at least two moles of a tertiary hydroperoxide of the formula:

Il i R1C--OOH where in all the aforementioned formulas R is an alkyl and R is an aryl or alkyl in the presence of an acid condensation catalyst.

The reaction is carried out at temperatures below about 40C..The acid catalyst is added slowly to the alcohol to maintain the temperature in the range 0 to 5C. so as to minimize dehydration of the alcohol. Once the acid is added, the reaction temperature is allowed to go up to room temperature or higher e.g.'40C. to

increase the reaction rate following the addition of the tertiary hydroperoxide.

It is not necessary to use a solvent in performing the reaction. However, an organic solvent such as ether, benzene, toluene and the like may be employed if desired. I

The acids operable as a catalyst in this invention include sulfuric acid, phosphoric acid, p-toluene sulfonic acid and other acid condensation catalysts well known to those skilled in the art. The amount of acid employed as a catalyst is not critical. Ac'id amounts in the 0 range 0.05 to 1 mole of acid per mole of hydroxyl group in the tertiary alcohol are operable in practising this invention. It should be remembered, however, that the acid catalyst is preferably added slowly to the alcohol at low temperatures, e.g. about 0C. to insure that the alcohol is not dehydrated.

.The tertiary alcohols of the formula 3 I decylphthalyl, and'aaa'a tetradecyl terephthalyl alcohol. An example will be given hereinafter showing the preparation of the tertiary alcohols reactants.

The tertiary hydroperoxides of the formula 7 EXAMPLE I PREPARATION OF A TERTIARY ALCOHOL To a I i-necked, round bottom liter flask equipped with reflux condenser and stirrer containing 1,000 ml. of absolute ether was added 105.6 g. Mg followed by the addition of 624.8 g. methyl iodide in 1,000 ml.'of absolute ether (diethyl oxide). 194. g. Dimethyl isophthalate in 1,200 ml. absolute ether was slowly added with stirring to the flask. The reaction was continued for 16 hours at about 37C. The Grignard complex was decomposed with aqueous hydrochloric acid. The aqueous layer containing MgCl was removed in a separatory funnel. The ether layer was evaporated to dryness and the residue crystallized from methanol. The aaaatetramethyl isophthalyl alcohol residue product, i.e.

weighed 89 g. and had a melting point of l38-l40C.

EXAMPLE 2 To a 250 m1.'3 necked round bottom flask equipped with stirrer, dropping funnel, and a thermometer was added 19.4 g. of aaaa' tetramethylisophthalyl alcohol from Example 1. 28 ml. of 70% sulfuric acid was slowly added to the flask while maintaining a temperature of O0 C(CHzla CHa-(E-CH:

(EH: c'0 0 C (CH1); OH;

weighed 28 g. and analyzed 76 percent pure. The yield was 82.5 percent of theory based on the weight of the alcohol reactant. 1

EXAMPLE 3 Using the equipment and procedure of Example 2,

except that 43.4,g. of 70% cumene hydroperoxide,

oxide in Example 2, resulted in a 1,3 bis(cumylperoxyisopropyl) benzene product,

The bisperoxides prepared in accord with the instant invention are especially/useful as crosslinking agents for polyethylene. More particularly high density (0.94-0.97) polyethylene, see for example, U.S. Pat.

No. 2,816,883, has inferior clarity as compared to conventional low density (0.92) polyethylene. The art has discovered that crosslinking of high density improves the clarity thereof. The problem remains however, that with high density polyethylene having a melting point of 125-137C. it is difficult to find a crosslinking agent with a decomposition temperature high enough to allowdecomposition to take place at or above the softening point of the polymer.

The bisperoxides 1 herein disclosed are capable of cross-linking high density polyethylene.

in the following examples, the melt indices (Ml) were measured under the conditions specified in ASTMD 1238-52T, the densities of the polymer were measured in a density gradient tube by the Bell Laboratories Proposed ASTM Method for the Measurement of Density of solid plastics by the density gradient techniques.

Unless otherwise noted, a Brabender Plastograph Model PL-V2 equipped with a recording unit for meaever, other mechanisms, e.g. a Banbury mixer or a tape extruder are equally operable, for the blending step.

The degree of crosslinking is related to the increase in torque (Ar) measured by the Plastograph Recorder from the time the bisperoxide crosslinking agent is added to the fused polymer until the crosslinking reaction is discontinued. The greater the degree of crosslinking the greater the viscosity of the polyethylene, which in turn requires greater torque in order to drive the Plastograph at a constant rpm. The degree of crosslinking which can be accomplished is limited only by the ability of the mixing apparatus to overcome the torque caused by the crosslinking.

A further check on the degree of crosslinking is the decrease in melt index due to crosslinking of the polyethylene. Since melt index varies inversely with viscosity which varies directly with degree of crosslinking, a lower M1 after cross-linking evidences that crosslinking occurred.

Unless otherwise noted, all parts and percentages are by weight in the following examples.

EXAMPLE 4 CH3 CH3 Ha CH3 in benzene was added to the fused polymer and milling continued for 2 minutes. A1- was 3780 units. The crosslinked polyethylene on characterization had a melt index of 0.0. I

EXAMPLE 5 38 g. commercial polyethylene in granule form having a melt index of 0.7 and a density of 0.96 were charged over a 4 minute period to a Brabender Plastograph maintained at a temperature of C. After 14 minutes, 1.0 cc. of a 52 percent solution of aaa'a tetramethyl isophthalyl di-cumyl bisperoxide; also known 'as 1,3 bis(cumylperoxyisopropyl) benzene:

in benzene was added to the fused polyethylene and milling was continued for an additional 7 minutes at which time Ar was 520 units. The thus-crosslinked polyethylene had a melt index of 0.00.

The use of the novel bisperoxides as crosslinking agents for polyethylene is disclosed and claimed in a copending application filed-Jan. 7, 1960 having Ser. No. 946'now US. Pat. No. 3,118,866, issued Jan. 21, 1964 and assigned to the same assignee.

We claim:

1. As a composition of matter, a tertiary-tertiary aralkyl bisperoxide of the formula:

i i t -rt w i r R, It R R1 wherein R is a straight chain alkyl containing 1 to 10 carbon atoms and R is a member of the radical group consisting of tertiary butyl, a cumyl, diisopropylphenyl, methyl, paratertiary-butyl-a-cumyl, decalyl and triphenylmethyl.

2. As a composition of matter, 1,3 bis(t-butylperoxyisopropyl) benzene.

3. As a composition of matter, 1,3 bis(cumylperoxyisopropyl) benzene.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE 0F CQRRECTIQN PATENT N0. 3,764,628

DATED October 9, 1973 INVENTOMS): Ramzic S. GREGORIAN et al Cover page, second line, immediately before "October 9, 1973" insert an asterisk Same page, left column, after the "Assignee" line, insert:

-[*] Notice. The portion of the term of this patent subsequent to January 21, 1981 has been disclaimed.

gigncd and gcalzd this Ninth D y Of May 1978 RU'I'H (L \l,-\.\()\ l.U l'RH.l,l-'. F. PARKER :lrlmling (If/ice! {cling (nmmiuium'r of Parents and Trademarks I mg?) MI-TED ES lATE oE FEcE CERTEFKCATE Q9 Patent No. ,764,628 m ma October 9, 1973 Inventor) Razmic' S. Gregorian and Richard A. Bafford I It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as ahmm below:

. F In Claim 1, column 6, between lines 28 and 34;, the "a formula should read as follows:

. I I R -o-o-t OOR Signedand sealed this 5th day of February 1974.

tSEliLj Attest: I EDWARD M.FLETCHER,JR. RENE D. TEGTMEYER. Attesting Officer Acting Commissioner of Patents 

2. As a composition of matter, 1,3 bis(t-butylperoxyisopropyl) benzene.
 3. As a composition of matter, 1,3 bis(cumylperoxyisopropyl) benzene. 